Lamp holder



J. M. PISTEY Filed May 29, 1951 Inventor":

' I/ John MP1 v. 40 l v by Hi8 Attoneg.

United States Patent'O LAMP HOLDER John M. Pistey, Fairfield, 001111.,assignor to General Electric Company, a corporation of New YorkApplication May 29, 1951, Serial No. 228,923

4 Claims. (Cl. 339-55) This invention relates to lampholders and, inparticular,'to a new and improved lampholder for a single pin dischargelamp.

Single pin discharge lamps and circuits used for energizing them areexplained more completely 1n S. Patent 2,427,225, Mueller, assigned tothe same assignee as that of the present invention, but briefly aconventional circuit is one wherein one end of a lamp is inserted into alampholder which has a spring-biased contact. The spring-biased contactis compressed until the other end of the lamp can engage a lampholder atthe opposite end of the lamp. The lampholder having the spring-biasedcontact generally is the high voltage lampholder.

In the manufacture of lampholders of this type, particularly when thenumber produced runs into the millions, any cost reduction, no matterhow small, when multiplied by the number of units produced, amounts to asizable saving. A cost reduction, for example, can be brought about byreducing the number of parts required for assembly.

It is an object of this invention then to provide an improved lampholderhaving a minimum number of parts to be put together during assembly ofthe lampholder.

A high voltage end lampholder in one embodiment includes a plunger whichis movable axially within the housing. The plunger is biased by an axialforce of a coiled spring so that, in its free position, the plungerprotrudes outwardly from the housing. In connecting a lamp into thelampholder a lamp pin is inserted into an aperture in the plunger andaxial pressure on the lamp pushes the plunger back into the housing to aposition where the free end of the lamp can be inserted in the oppositelampholder. The spring-biased plunger requires stops of some sort toprevent it from being dislocated from the housing. Frequently, to effecta cost reduction, the housing is made with such a marginal amount ofmaterial that the housing" is shattered occasionally by flicking theplunger and letting the spring drive the plunger against the stops.

It is a further object of this invention, therefore, to

provide an improved stop arrangement for controlling the limit of theplunger extending from the housing while maintaining the marginal amountof material.

In providing an electric contact in the high voltage end of alampholder, current is usually conducted into a coil spring which, inturn, is electrically connected to a screw terminal by a contact strip.It is possible for dirt or corrosion to deposit on either the contactstrip or the coil spring thereby preventing good electrical contactbetween them. This connection of the two parts generally is in a part ofthe lampholder that is not easily icci'gssible for cleaning withoutdisassembling the lamp- It is a further object of this invention,therefore, to

provide an improved coil spring, contact strip, and ter- -minal screwassembly wherein, by making one connection to the terminal screw, poweris supplied directly to the spring-biased contact.

In connecting lampholders of the subject type into an electricalcircuit, the Underwriters Laboratories Inc. re-

quires the positioning of an insulating strip between the terminal screwand a metal mounting surface. This insulating strip must be displaceablefrom the terminal screw in order to connect the lampholder into theelec- "ice trical circuit and then the strip must be replaceable afterthe connection has been made.

It is a further object of this invention, therefore, to provide animproved insulating strip positioning means for use with a lampholder.

Further objects and advantages of this invention will become apparentand the invention will be more clearly understood from the followingdescription, referring to the accompanying drawing, and the features ofnovelty which characterize this invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

Briefly, this invention relates to an improved lampholder for the highvoltage end of a discharge tube. The lampholder comprises a housing, aplunger, a new stop structure which increases the area of contactbetween the plunger and housing 1, an integral spring-biased contact,contact strip, and terminal screw, an insulating plate for protecting aterminal screw, and a new structure for locking the insulating plate ineither a closed or open position.

In the drawing:

Figure l is a cross-sectional view taken along the lines 1-1 of Figure2.

Figure 2 is an end view partially cut away of the lampholder shown inFigure 1.

Figure 3 is a view taken along the lines 33 of Figure 2 of the housingshowing the cooperation between an ear of the plunger and a stop on thehousing.

Figure 4 is a side elevational view of the lower portion of thelampholder of Figure 1 with the side wall removed to show the electricalconnection between the terminal screw and the spring contact with theinsulating strip shown in the closed position.

Figure 5 is a view similar to Figure 4 but showing the improvedinsulating strip in an open position. I

Figure 6 is a bottom view of the lampholder of Figure 4.

Figure 7 is a bottom plan view similar to Figure 6 but showing theinsulating strip in an open position.

In the drawing the lampholder 1 is shown as comprising a housing 2, aplunger 3, a combined springbiased terminal and contact strip 4, aninsulating strip 5, and a back cover 6.

Housing 2 is molded integrally from one of the phenol resins to providea base 7, a body 8, and a plunger receiving cylindrical aperture 9. Base7 is formed to have a conductor receiving notch 10 for connecting thelampholder in electrical circuit and a screw receiving channel 11 formounting the lampholder on a base.

Body 8 has apertures 12 for receiving connecting screws 13, while theplunger receiving cylindrical aperture 9 is formed to include a pair ofarcuate-shaped extensions 14 which assist in providing a cylindricalwall for the smooth axial guiding of plunger 3.

Plunger 3, which has a pair of ears 15 disposed apart, is a hollowcylinder having a central axial bore 16 and an end closure 17 which, inturn, defines a smaller axial opening 18 in alignment with bore 16 foradmitting a pin of the discharge lamp. Plunger 3 also is molded from oneof the phenolic resins.

Body 8 is further provided with a pair of channels 19 which cooperatewith cars 15 on plunger 3 to effect a purely axial movement for plunger3 into and out of housing 2. Channels or slots 19 are provided at oneend with a stop 20 so formed that a pair of shoulders 21 and 22 areproduced one on either side of an extension 23. The purpose of thisstructure is to insure other than a line contact between the ears 15 onplunger 3 and the stop 20. If purely line contact existed, then therewould be danger of breaking the housing at the point 23 of marginalthickness when plunger 3 is flicked.

The spaced shoulders 21 and 22 were designed to increase thecross-sectional shear area at the points of breakage. It is importantthat the clearance between the blunt end portion of the cars 15 and thepoint 23 at the end of the channels 19 be maintained. Otherwise, theshoulders 21 and 22 will be ineffective and breakage of either thehousing or the ears of the plunger will take place when the spring slamsthe plunger into its outermost position. This slamming action may takeplace when an attempt is made to insert the contact pin of the lamp intothe opening 18. If the contact pin does not enter the opening 18 and theplunger is depressed so that the other end of the lamp may be mounted inits cooperating lampholder, it often happens that the con tact pin willslip oil the plunger. This is when breakage is likely to take place. Thespring drives the ears of the plunger against the ends of the channels'19 in a forceful manner.

Spring contact 4 comprises a coil spring 25, a con tact strip 26, aterminal screw 27, and a terminal plate 28. Spring contact 4 is formedby winding coil integral with one end of the contact strip 26. The coil25 has an external diameter which permits it to be positioned Within thecentral axial bore 16 of plunger 3. The opposite end of contact portion26 is welded, or otherwise secured, to the terminal plate 28 which, inturn, is provided with a threaded bore 29 for receiving terminal screw27. Such an integral spring contact structure can be pre-assembled bymachines and consequently in assembly of the lampholder, a singleelement 4 will perform as both a spring-biased terminal and a contactstrip.

Rear cover 6 of housing 2 includes a protrusion 30 which extends intothe housing to complement both the body 8 and the base 7 to provide animproved lampholder. For example, the protrusion 30 includes a centralmember 31 having its upper end shaped in agreement with the contour ofplunger 3. Then when rear cover 61 is assembled with housing 2, centralmember 31 cooperates with the arcuate extensions 14 on housing 2 tofurther the formation of a smooth cylinder in which plunger 3 cantravel.

Protrusion 30, at one side of the central member 31, has a channel 32into which contact strip 26 of the spring contact 4 can be placed.Channel 32 cooperates with a socket 33 in protrusion 30 which engagesand supports terminal plate 28 of the spring contact 4.

The contact strip 26 of the spring 4, after passing through channel 32,is bent so that it engages a portion of rear cover 6, which has a slot34, shown in Fig. l, for recessing the contact portion 26 whereby theinterrelation of housing 2, plunger 3, and rear cover 6, is not impairedby the contact portion 26.

To insure electrical contact between spring 4 and a pin of the lamp, ametal disk 35 is positioned within the axial bore 16 of plunger 3 toengage the free end of spring contact 4. Then when the lamp pin isinserted through aperture 18 in plunger 3, the metal disk'connectsspring 4 to the lamp pin.

In assembling this lampholder, plunger 3 is placed into housing 2 andmetal disk 35 is placed into the axial opening 16 of plunger 3. Thecombined spring contact 4 is then positioned in place on the rear cover6 which, in turn, is positioned into engagement with housing 2. Underthese conditions, the spring contact 4 passes into central opening 16 ofplunger 3 to press against the metal disk 35 and the ears 15 on plunger3 are in engagement with stop Ztl on housing 2. The housing is thenretained in assembled position by passing screws 13 through apertures 12in body 8 to engage threaded bores 36 contained in protrusion 30.

While the lampholder as thus far described will operate and function toenergize a lamp, the Underwriters Laboratories Inc. requires that aninsulating strip, such as that shown at 5, be positioned between theterminal screw 27 and a metal mounting surface on which the lampholderis to be positioned.

Insulating strip 5 is substantially rectangular, except that it includesa pair of cars 37 and a notch- 38. The base 7 of housing 2 is providedwith notches 39 which cooperate one with each of the cars 37. The cars37 of the insulating strip 5,. when positioned into the notches, areheld there for rotatable support of the strip 5 relative to the base 7of the lampholder.

The base 7 further has a pair of protrusions 40 for engaging the end ofstrip 5 opposite cars 37, i. e.,v when strip 5 is closed into contactwith base 7 the strip 5 is forced past the protrusions 40 as strip 5,which has some resilient properties, is deformed. After passing theprotrusions 40, insulating strip 5 regains its. original shape to beretained in the closed position by the protrusions 40. p

A unique feature of this insulating strip 5 is its cooperation with aprotrusion 41 formed on the back cover 6 of the housing, i. e., the ears37, which cooperate with the notches 39 to provide support of theinsulating strip 5, retain the outer ends of the strip 5 while thecenter of the strip 5 adjacent the notch 38 comes into contact with theprotrusion 41 on the back cover 6 whereby the strip 5 is deformed tomaintain it in an open position for easy access to the terminal screw27.

Looking at Figure 5, it is seen that when the insulating strip 5 ispivoted to its open position, the marginal edge of the strip adjacentits hinged axis scrapes against the bottom wall of the base 7.

In order to maintain the insulating strip 5 in the open position, theprotrusion 41 is formed in cooperation with the notches 39 to bow thestrip 5 outwardly in the center. Consequently, the contact of the strip5 with the bottom of the base 7 is not along a straight line but alonga. curved line as is clearly seen in Figure 7.

Therefore, in wiring this improved lampholder, it is not necessary as insome prior art arrangements to hold the insulating strip open with onehand, leaving only the other hand for completing the operation, but theinsulating cover stays open leaving both hands free.

Modifications of this invention will occur to those skilled in the artand it is desired to be understood, therefore, that this invention isnot to be limited to particular embodiment disclosed, but that theappended claims are meant to cover all the modifications which areWithin the spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An improved fluorescent lampholder comprising a housing, a movableplunger for receiving the contact pin of a fluorescent lamp, acurrent-carrying spring member for operating said plunger andforelectrical connection with said contact pin, said housing havinginternally thereof a pair of spaced parallel slots cooperating with apair of external ears on the said movable plunger for guiding themovement thereof, the outer ends of said slots being closed by end Wallsto limit the outward movement of the plunger, each of said walls havinga recessed control portion so that contact between each slot end walland the cooperating plunger ear is made over spaced areas.

2. In an improved fluorescent lampholder comprising a hollow housing of.insulating material, electrical contact means within the housing forcooperation with a lamp base, and outwardly exposed terminal meansjoined with the said contact means for connecting said lampholder in anelectric circuit, a pair of opposed notches formed in said housingadjacent said terminal means, and a pivoted insulated strip of resilientmaterial for covering the said terminal means of said lampholder, saidstrip being pivotally mounted by means of spaced ears seated in saidnotches, and a projection formed on said housing adjacent the pivotaledge of the strip for hearing against the outer surface of said strip todeform and hold the strip in a transversely arcuate shape when the stripis pivoted to its final open position.

3. In a fluorescent lampholder as recited incl'aim 2 wherein the pivotaledge of the insulating strip while in its final open. positionfrictionally bears against an outer wall of said housing.

4. In a fluorescent larnpholder as recited in claim 2 whereinthe saidpivotal edge of the insulating strip is formedwith a notch to provideclearance between the housing projection and the strip while the stripis in its closed position.

References Cited: in the file of this patent UNITED STATES PATENTSNumber Name Date 2,237,362 Rieman Apr. 8,1941 2,427,225 Mueller Sept. 9,1947 2,447,676 Webster Aug. 24, P948 2,461,135 Bently Feb. 9', F9492,464,643 Kulka Mar. 15-, 1949 2,495,196 Kulka- Ian: 17', 1950 2,604,595DeReamer Italy 22, 1952 FOREIGN PATENTS Number Country Date 464,805Canada May 2, 1950

